Spring charging mechanism for a circuit breaker



Dec. 6, 1966 H. L. lVlNS 3 SFRING CHARGING MECHANISM FOR A CIRCUITBREAKER Filed June 16, 1965 {5 sheetswSheet l H. L. IVIN5 Dec. 6, 1966SPRING CHARGING MECHANISM FOR A CIRCUIT BREAKER Filed June 16, 1965 5Sheets-5heet 0 Q 0 i EL ZIZZE" 50 1547a y. W

Dec. 6, 1966 H. 1 wms 3,289,79U

SPRING CHARGING MECHANISM FOR A CIRCUIT BREAKER Filed June 16, 1965 5Sheets-Sheet 5 United States Patent 3,289,790 SPRING CHARGING MECHANISMFOR A CIRUUIT BREAKER Herbert L. Ivins, Cleveland, ()hio, assignor toSquare 1) Company, Park Ridge, Ill., a corporation of Michigan FiledJune 16, 1965, Ser. No. 464,338 Claims. (Cl. 18539) This inventionrelates to a mechanism for charging springs, and more particularly to aspring-charging mechanism for charging the closing springs of a powercircuit breaker.

Because the current flowing upon the initial engagement of the contactsof a power circuit breaker during a closing operation can result inlarge forces tending to drive the circuit breaker to its open position,it is necessary to have considerable mechanical energy available if theclosing operation is to be completed. When the force required tocompletely close a circuit breaker under all possible circuit conditionsis in excess of that which can be imparted manually, or by a solenoid ormotor of reasonable size, closure is often effected by releasingmechanical energy previously stored in closing springs which have beenprecharged by intermittent operation of a manually driven crank or by amotor.

In accordance with the present invention, there is provided an improvedspring-charging mechanism in which a crank or lever is manually movablethrough an indefinite number of strokes of indefinite length to chargethe closing springs of a circuit breaker in descrete steps. Themechanical advantage of the charging crank is augmented by a cam whichalso serves as a motion converter. An improved clutch, operativelyinterposed between the crank shaft and the cam, permits the charging ofthe springs by short repeated strokes of the crank with the crank beingpositionable by the operator for the most convenient and efficientapplication of manual force. The mechanism is such that rotation of thecam can be effected either automatically by an electric motor ormanually by the crank.

It is an object of this invention to provide an improved spring-chargingmechanism for charging the closing springs of a circuit breaker.

Another object is to provide a spring-charging mechanism for a circuitbreaker which includes an improved clutch operatively interposed betweena manually operable crank and a charging cam.

Another object is to provide an improved springcharging mechanism forcharging the closing springs of a circuit breaker in which the springsare compressed by a cam rotated selectively through a one-way clutcheither by manual force exerted on a crank or directly by an electricmotor which may be controlled from a remote point.

Other objects and advantages will become apparent from the followingdescription wherein reference is made to the drawings, in which:

FIG. 1 is a frontal perspective view of a spring-charging mechanism inaccordance with this invention with the springs in the unchargedcondition and showing a portion of a circuit breaker with which themechanism may be used;

FIG. 2 is a front elevation view of the mechanism of FIG. 1;

FIG. 3 is a fragmentary side elevational view, partly in section, of themechanism of FIG. 1;

FIG. 4 is a fragmentary sectional view taken as indicated at 4-4 in FIG.3 showing a stop means of the mechanism;

FIG. 5 is a cross sectional view of an operating shaft and spring clutchassembly;

FIG. 6 through 8 are views of an operating mechanism 3,289,790 PatentedDec. 6, 1966 "ice of an exemplary circuit breaker with which thespringcharging mechanism of FIGS. 1 through 5 may be used and whereinthe uncharged, open-charged, and closed-uncharged positions are shown,respectively;

FIG. 9 shows another embodiment of the invention in which thespring-charging mechanism of FIGS. 1 through 5 is modified for operationeither by an electric motor or manually; and

FIG. 10 is a view similar to FIG. 4 but showing a portion of themodification of FIG. 9.

Referring to the drawings, a spring-charging mechanism 10 in accordancewith this invention is shown as arranged to charge a pair of springs 11for effecting closure of a circuit breaker. Although it may be used withcircuit breaker operating mechanism of different types, thespringcharging mechanism 10 is illustrated in connection with a circuitbreaker operating mechanism 12 shown in FIGS. 6 through 8 for which itis particularly suited,

Referring to FIGS. 6 through 8, the circuit breaker operating mechanism12 comprises, among other components, a plurality of fixed pivot shafts14 through 20, appropriately marked with the symbol F to indicate thatthey are fixed, and which are suitably supported at opposite ends insides plates 21 (FIGS. 1 and 2), a plurality of displaceable pivotshafts 24 through 2 8, a closing crank link 34, a contact closing crank35, a main trip latch 36, a secondary closing latch 38, a main closinglatch 39, a drive crank 40, a pair of spaced drive links 41, a secondarytrip latch 42, a gauging crank 45, and a ganging crank link 46, all ofwhich are arranged to move pairs of contacts 48a and 48b on respectivemovable contact structures 49 into and out of engagement with respectivepairs of stationary contacts Stla and Stlb. Although only one contactstructure 49 is shown in FIGS. 6, 7, and 8, it is to be understood thatthere are three contact structures 49 driven by the operating mechanism12 and interconnected by an interconnecting portion 45a of the gangingcrank 45.

The drive crank 4t) which is in the form of a bell crank is pivoted onthe fixed shaft 17 and has an arm portion 40a pivoted on thedisplaceable shaft 25 on which the drive links 41 are also pivoted.While the closing springs 11 are being compressed, the displaceableshaft 25 moves downwardly from the position of FIG. 6 representing theuncharged, open-contact position, to the position of FIG. 7 wherein thesprings 11 are fully charged. The downward movement of the shaft 25pivots the drive crank 40 counterclockwise about its pivot shaft 17.When the drive crank 40 reaches the position of FIG. 7, the main closinglatch 39, which is biased in a counterclockwise direction by a spring39a positioned about the fixed pivot shaft 16, turns counterclockwise sothat a shoulder portion 39b thereon captivates a roller 40b on an armportion 400 of the crank 40. The main closing latch 39 is releasablyheld in this latching position by the action of the secondary closinglatch 38. The secondary closing latch 38 is springbiased in a clockwisedirection by a spring (not shown) about its fixed pivot shaft 15 so thatan arm 38a thereof, upon the spring 11 becoming fully charged, abuts aroller on the main closing latch 39 thereby to hold the springs 11 inthe charged condition preparatory to a contact-closing operation.

Concurrently, the downward movement of the displaceable shaft 25 drawsthe spaced drive links 41 downwardly and in turn causes clockwiserotation of the closing cam 44 around its fixed pivot shaft 19 todisengage the forward portion of the closing cam 44 from the movablepivot shaft 28. This permits the collapse of the toggle linkagecomprising the links 34 and 46 from the position of FIG. 6 to theposition shown in FIG. 7. The consequent downward movement of themovable shaft 28 causes counterclockwise rotation of the contact-closingcrank 35 around its fixed pivot shaft 14. The crank 35 rotates until theposition of FIG. 7 is reached where an arm portino 36a of the main triplatch 36 abuts a roller 35a on the closing crank 35 and latches theclosing crank 35 in a substantially horizontal position. The secondarytrip latch 42 is biased counterclockwise by a spring (not shown) andturns counterclockwise to the position of FIG. 7 where a forward portion42a abuts a roller 36b on the main latch 36,

The operating mechanism 12 is now in the position of FIG. 7 with thesprings 11 charged preparatory to closing the contacts 4858. To effectsuch closure, the secondary closing latch 38 is, by means hereinafterdescribed, rotated about its fixed pivot shaft in a counterclockwisedirection thereby releasing the main closing latch 39 which, in turn,releases the drive crank 41 The drive crank 40 is then free to rotate ina clockwise direction around the fixed pivot shaft 17. The closingsprings 11 expand and the movable shaft moves upward sharply. Since thecontact-closing crank has been rotated and latched by the main triplatch 36 in a substantially horizontal position, the thrust of thesprings 11 is directed along the longitudinal axis of the drive links 41and is translated into a lateral force directed to the left as viewed inFIGS. 6, 7, and 8 by the closing cam 44 and the toggle linkagecomprising the links 34 and 46. This turns the ganging crank 45counterclockwise around its fixed pivot shaft 19 thereby to effectclosure of the contacts 48-50. At the same time, a pair ofparallel-spaced opening springs 51 connected between the gauging crank45 and respective fixed points on the side plates 21 are extended by therotation of the ganging crank 45.

To effect opening of the contacts 48-50, the secondary trip latch 42 isrotated, by means not shown, in a clockwise direction out of engagementwith the main trip latch 36. The bias of the opening springs 51 actingthrough the links 34 and 46 and the closing crank 35 forces the maintrip latch 36 to rotate in a clockwise direction permitting the closingcrank 35 to rotate clockwise to the position of FIG. 6. The contacts48-50 are then forced vigorously apart by the contraction of the openingsprings 51 which turn the ganginng crank 45 clockwise to the position ofFIG. 6.

Referring now to FIG. 1, the means for operating the secondary closinglatch 38 comprises a closing operator 54 on the front of the circuitbreaker having a protruding button portion 54a secured to an anglebracket 54b slidably mounted at the upper end portion of one of the sideplates 21. To effect a closing operation, the operator 54 is movedrearwardly against the bias of a spring (not shown) to cause a shoulderportion 58 on the bracket 54b to engage a crank 59 thereby to effectrotation of a shaft 60 secured to the crank 59 and rotatably supportedat opposite ends by the respective side plates 21. Upon rotation of theshaft 60, a crank 61 thereon lifts a rod 62 secured at its lower end toone arm of the closing latch 38 causing the latch 38 to rotate in acounterclockwise direction as viewed in FIGS. 6, 7, and 8. As previouslydescribed, counterclockwise rotation of the secondary closing latch 38unlatches the main closing latch 39, and the stored energy in thesprings 11 is then transmitted to the drive links 41 whereby the movablecontacts 48 are moved rapidly and with adequate force into engagementwith the stationary contacts 50.

It is thus seen that, during charging of the springs 11, the shaft 25moves downwardly from the position of FIG. 6 to the position of FIG. 7to condition the operating mechanism 12 for a subsequent closingoperation. The closing latches 38 and 39 maintain the operatingmechanism 12 in this position until operation of the operator 54releases the latch 38. Upon such release, the springs 11 move the shaft25 upwardly to eflect the closing operation of the contacts 48-50.

Referring now to FIGS. 1 through 4, spaced side walls 64 of the circuitbreaker support an angle bracket 65 therebetween which carries thecharging mechanism 10 of this invention. A pair of bolts 66 passingthrough openings in a vertical wall of the bracket 65 hold a rearsupport plate 68 against the vertical wall of the bracket 65. Spacedforwardly from the rear support plate 68 by spacers 78 (FIG. 3) andsupported by the bolts 56 is a front support plate '71. A pair of bolts72 passing through openings in the plates 68 and 71 support a controlplate 74 forwardly of the front support plate 71 and a rear plate 75rearwardly of the rear support plate 68.

The plates as, 71, 74, and 75 serve as hearing supports for an operatingshaft assembly (best seen in FIG. 5) comprising three coaxial shafts 78, 7 9, and of uniform outside diameter. Keyed to the intermediate shaft79 is an operating cam 81 which engages a cam follower 82 rotatablymounted between a pair of horizontally-disposed, spaced bars 8-4supported at opposite ends by a pair of spring-drive rods Each of therods '85 comprises a rectangular upper portion 86 and a cylindricallower portion 88. The portions 86 and 88 may be joined by a keyedconnection as shown. The lower end faces of the rectangular portions 86bear against respective upper spring holders 89 positioned at the top ofthe respective springs 11 which surround the respective rod portions 88and which, at their lower ends, are held by spring seats 98 secured tothe respective side plates 21 as by screws 90a. The lower end portionsof the rod portions 88 pass through respective openings in the springseats 91 and are threaded into respective openings near opposite ends ofthe shaft 25 of the operating mechanism 12 thus to secure the shaft 25to the rods 85.

Surrounding adjacent portions of the shafts 79 and 80 is a helicalspring 91 and surrounding adjacent portions of the shafts 78 and 79 is ahelical spring 92. One end of the spring 91 is secured to the shaft 79as by a pin 91a (FIG. 3) and one end of the spring 92 is secured to theshaft 79 as by a pin 92a. The other end of the spring 92 is free, andthe other end of the spring 91 is in driving engagement with a stopmeans to be described.

The shafts 79 and 80 are maintained in coaxial relationship by receptionof an axially projecting portion 79a of the shaft 79 in a complementaryaxial recess 80a in the shaft 80. In the absence of the spring 91, theshafts 79 and 80 would be free to rotate relative to each other ineither direction. In like manner, the shafts 78 and 79 are maintained ina coaxial relationship by reception of an axially projecting portion 78aof the shaft 78 in an axial complementary recess 7% of the shaft 79. Inthe absence of the spring 92, the shaft 79 would be free to rotaterelative to the shaft 78 in either direction. The shaft 78 has aserrated end portion 78b inserted in a like serrated opening in the rearplate 75 to firmly fix the shaft 78 against rotation.

The spring 91 is so wound that clockwise rotation of the shaft 80 (asviewed in FIGS. 1 and 2) causes the spring 91 to be radially contractedthereby to tighten the con- Volutions thereof firmly about the shafts 79and 80 to cause the shafts to rotate as a unit. Upon counterclockwiserotation of the shaft 80, the spring 91 expands and permits relativerotation between the shafts 79 and 80. The spring 92 is so wound thatclockwise rotation of the shaft 79 (as viewed in FIGS. 1 and 2) causesradial expansion or unwrapping of the spring 92, thereby permitting theshaft 79 and the cam 81 to rotate freely in a clockwise direction tocharge the springs 11. The shaft 79 cannot rotate in thecounterclockwise direction because any tendency to do so causescontraction of the spring 92 about the shafts 78 and 79.

When the spring 91 secures the shafts 79 and 80 together in order tocause them to rotate together, the spring 92 is released to permit theshaft 79 to rotate relative to the fixed shaft 78. Conversely, when itis desired to rotate the shaft 80 relative to the shaft 79 preparatoryto a subsequent charging stroke, the spring 92 prevents movement of theshaft 79 in a counterclockwise direction relative to the shaft 78. Inthis manner, any number of clockwise charging strokes of any length of acrank or lever 94 releasably mounted on the forward end portion of theshaft 80 convenient to the operator may be used to charge the springs11, and each stroke may be started, without lost motion, at any turnedposition of the shaft 80. At the completion of a charging stroke, thecrank 94 may be moved counterclockwise freely because the spring 91expands to permit rotation of the shaft 80 relative to the shaft 79.This enables the crank 94 to be re-positioned for convenient applicationof manual force.

While the shaft 79 turns by force exerted on the crank 94, the cam 81turns to drive the bars 84 downward to charge the springs 11.

The shaft 80 is effectively disconnected from the main drive shaft 79when the springs 11 are fully charged, so that further rotation of theshaft 80 by the crank 94 has no effect. This is accomplished by a stopmeans comprising a disc 100, rotatably mounted on the shaft 80, and anL-shaped trip lever 101 having a vertical arm 101a and a horizontal arm101k. The lever 101 is pivotably mounted intermediate its ends on a pin102 carried by the front support plate 74 as shown in FIGS. 1, 2, and 4.A spring 104 is connected between a post 105 located on an upper portionof the plate 74 and a like post 106 aflixed to the outer end portion ofthe vertical arm 101a of the lever 101 so as to normally bias the sameinwardly about the pin 102. As best seen in FIG. 4, a pair of spacedears 107 is provided on the disc 100 which receive therebetween anoutwardly turned portion 91b of the otherwise free-end portion of thehelical spring 91. The disc 100 is free to rotate on the drive shaft 80and is essentially circular in configuration with an indentation 100atherein forming a shoulder stop 10012.

When the springs 11 are uncharged, a post 108 extending forwardly fromthe front one of the support bars 84 (FIG. 1) engages an end portion ofthe horizontal arm 101b of the trip lever 101 to pivot the vertical arm101a about the pin 102 against the bias of the spring 104 in a clockwisedirection as viewed in FIGS. 1 and 2 to a position where the post 106 isbeyond the outermost limits of the peripheral edge of the disc 100.Under these conditions, when the crank 94 drives the shaft 80, thehelical spring 91 is radially contracted as previously describedwherebythe convolutions thereof are securely tightened around the shafts 79 and80 and cause them to rotate in unison. The spring 91thus turns with theshafts 79v and 80 and the end portion 91b positioned between the ears107 and bearing against the uppermost one as viewed in FIG. 4 causes therotation of the disc 100. The disc 100 thus rotates clockwise as viewedin FIG. 2 in unison with the shafts 79 and 80 until, the indentation100a is opposite the pin 106. The spring 104 then pivots the verticalarm 101a of the lever 101 inwardly about the pin 102 to the position ofFIGS. 2 and 4. The disc 100 is now prevented from further rotation bythe post 106 abutting the shoulder stop When the disc 100 is held inthis position, the spring end portion 91b is also held in fixed positionby the ears 107, and further rotation of the shaft 80 causes theconvolutions of the spring 91 to open thereby to disconnect the shaft 80from the main drive shaft 79. Thus it is seen that further rotation ofshaft 80 has no effect. The cam 81 has now been turned to the positionof FIG. 2 and has charged the springs 11 by effecting downward movementof the bars 84.

The disc 100 is maintained in this nonrotatable position until thesprings 11 are discharged whereupon the post 108 moves in the upwarddirection and, by engagement with the end portion of the horizontal arm1011: of the lever 101, causes the vertical arm 101a to move to aposition where the post 106 again clears the edge of the disc 100 topermit the disc to rotate as previously described.

The foregoing description with reference to FIGS. 1 through 5 pertainsto the operation of the spring-charging mechanism 10 by manual means,i.e., by rotating the shaft 80 by use of the crank 94. In thisembodiment, the

shaft portion 78 is fixed to the rear support plate 74 and isnon-rotatable.

In the embodiment of the invention shown in FIGS. 9 and 10, whichpermits operation of the spring-charging mechanism 10 either manually orby an electric motor 110 mounted on the horizontal support bracket 65,the motor 110 includes a worm drive section 110a positioned tooperatively engage a portion of a shaft 78, which is substituted for theshaft 78 of the principal embodiment. The shaft 78 is rotatable relativeto the shaft 79 in the same manner as the shaft 80. Further, a secondrotatable disc 111 like the rotatable disc is provided on the shaft 78'and has a pair of cars 112 for receiving therebetween an outwardlyturned end portion 92b of the spring 92. A trip lever 113 is providedwhich is like the lever 101 and the pin 108 is made longer so as toengage the horizontal portion of the lever 113. Further the rear plate75 is replaced by a plate 75' shaped like the front plate 74.

When the springs 11 are in the uncharged condition, operation of themotor 110 rotates the drive shaft 78 causing the convolutions of thespring 92 to tighten about the shafts 78' and 79 thereby causing theshafts 78 and 79 to rotate in unison. The spring portion 92!) locatedbetween the ears 112 effects rotation of the disc 111 until a shoulderstop 1111) therein is reached and the trip lever 113 holds the disc 111stationary. The shaft 78' is now free to rotate with respect to the maindrive shaft 79. The disc 111 is held in the non-rotatable position untilthe springs 11 are discharged and the trip lever 113 is pivoted by thepin 108 to a position to free the disc 111 and allow it to rotate.

When the crank 94 is used to turn the shaft 84 of the embodiment ofFIGS. 9 and 10, the worm 110a locks the shaft 78' so that operation isas in the principal embodiment.

It will be noted that the spring closing mechanism 10 is operative tocharge the springs 11 when the circuit breaker operating mechanism 12 isin the position of FIG. 8 with the contacts 48-50 closed. This isbecause the shaft 25 is free to move downwardly without disturbing thetoggle-linkage comprising the links 34 and 46 so long as the main triplatch 36 is in the position of FIG. 8.

While only the specific embodiments of the invention shown in thedrawings have been described, it will be understood that variousmodifications and variations therefrom may be effected withoutmaterially departing from the true scope of the invention.

What is claimed is:

1. In a charging mechanism for a closing spring of a circuit breaker,means movable to compress the spring by engagement with an end thereof,a rotatable cam for moving said movable means, a first shaft fixed tosaid cam for rotating said cam, second and third shafts coaxial withsaid first shaft and extending respectively from opposite ends thereof,a first helical spring means surrounding at least a portion of each ofsaid first and second shafts and a second helical spring meanssurrounding at least a portion of each of said first and third shafts,said first spring means being operative to permit rotation of saidsecond shaft with respect to said first shaft in one direction and toprevent relative rotation therebetween for the opposite direction ofrotation, said third shaft being fixed against rotation, and said secondspring means being operative to permit relative rotation between saidfirst and third shafts in one direction only.

2. In a charging mechanism for a closing spring of a circuit breaker,the closing spring having a fixed end and an end movable to effectcompression of the spring, a pair of support plates carried by thecircuit breaker, a first shaft rotatably positioned between said supportplates and supported thereby, a rotatable cam fixed to said first shaftand positioned between said support plates, means interposed betweensaid rotatable cam and the movable end of the closing spring operable tocompress the spring when the cam is rotated, second and third shaftscoaxial with said first shaft and extending respectively from oppositeends thereof, said second shaft being rotatable and said third shaftbeing fixed, a first helical spring surrounding at least a portion ofsaid first and second shafts, a second helical spring surrounding atleast a portion of said first and third shafts, said first helicalspring having convolutions which contract about said first and secondshaft portions when said second shaft is rotated in one direction,whereby said first and second shafts rotate in unison, said convolutionsof said first helical spring loosening when said second shaft is rotatedin the opposite direction, said second helical spring havingconvolutions which loosen when said second shaft is rotated in said onedirection to permit said first and second shafts to rotate in unisonrelative to said third fixed shaft, said convolutions of said secondhelical spring contracting about said portions of said first and thirdshafts to hold the same in a fixed position when said second shaft isrotated in said opposite direction.

3. In a charging mechanism for a closing spring of a circuit breaker,the closing spring having a fixed end and an end movable to effectcompression of the spring, a pair of support plates carried by thecircuit breaker, a first shaft rotatably positioned between said supportplates and supported thereby, a rotatable cam fixed to said first shaftand positioned between said support plates, means interposed betweensaid rotatable cam and the movable end of the closing spring operable tocompress the spring when the cam is rotated, second and third shaftscoaxial with said first shaft and extending respectively from oppositeends thereof, said second shaft being rotatable and said third shaftbeing fixed, a first helical spring surrounding at least a portion ofsaid first and second shafts, a second helical spring surrounding atleast a portion of said first and third shafts, rotatable disc meanscarried on said second shaft and positioned between said first helicalspring and said first support plate, said disc means being rotatablerelative to said second shaft, said first helical spring having one endsecured to said first shaft and the other end secured to said rotatabledisc means, said second helical spring having one end secured to saidfirst shaft and the other end free, said first helical spring havingconvolutions which contract about said portions of said first and secondshafts when said second shaft is rotated in one direction whereby saidfirst and second shafts and said rotatable disc means rotate in unison,said convolutions of said first helical spring loosening when saidsecond shaft is rotated in the opposite direction, said second helicalspring having convolutions which loosen when said second shaft isrotated in said one direction to permit said first and second shafts andsaid rotatable disc means to rotate in unison relative to said thirdfixed shaft, said convolutions of said second helical spring contractingabout said portions of said first and third shafts to hold the same in afixed position when said second shaft is rotated in said oppositedirection, and stop means engaging said rotatable disc means to hold thedisc against further rotation at a predetermined turned positionthereof, whereby further rotation of said second shaft in said onedirection causes loosening of said convolutions of said first helicalspring from said second shaft, whereby said second shaft is free torotate relative to said first shaft.

4. In a charging device for a closing spring of a circuit breaker, animproved multi-section shaft and clutch mechanism comprising a firstshaft portion having a recess at one end and a reduced neck at the otherend, a second shaft portion having a recess at one end for rotatablyreceiving said reduced neck of said first shaft portion therein, saidrecess of said first shaft portion rotatably receiving a reduced neckportion of a third shaft portion, said shaft portions being alignedsubstantially coaxially, a first helical spring surrounding each of saidfirst and second shaft portions, a second helical spring surroundingeach of said first and third shaft portions, said first helical springhaving convolutions which contract about said first and second shaftportions when said second shaft portion is rotated in one direction,whereby said first and second shaft portions rotate in unison, saidconvolutions of said first helical spring loosening when said secondshaft portion is rotated in the opposite direction, said second helicalspring having convolutions which loosen when said second shaft portionis rotated in said one direction to permit said first and second shaftportions to rotate in unison relative to said third shaft portion, saidconvolutions of said second helical spring contracting about said firstand third shaft portions to hold the same in fixed relation to eachother when said second shaft rotates in said opposite direction.

5. In a charging mechanism for a closing spring of a circuit breaker,means movable to compress the spring by engagement with an end thereof,a rotatable cam for moving said movable means, a first shaft fixed tosaid cam for rotating said cam, second and third shafts coaxial withsaid first shaft and extending respectively from opposite ends thereof,a first helical spring means surrounding at least a portion of each ofsaid first and second shafts and a second helical spring meanssurrounding at least a portion of each of said first and third shafts,said first spring means being operative to permit rotation of saidsecond shaft with respect to said first shaft in one direction and toprevent relative rotation therebetween for the opposite direction ofrotation, an electric motor, gearing interposed between said motor andsaid third shaft permitting said motor to drive said third shaft andpreventing rotation of said third shaft except when driven by saidmotor, and said second spring means being operative to permit relativerotation between said first and third shafts in one direction only.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

1. IN A CHANGING MECHANISM FOR A CLOSING SPRING OF A CIRCUIT BREAKER, MEANS MOVABLE TO COMPRESS THE SPRING BY ENGAGEMENT WITH AN END THEREOF, A ROTATABLE CAM FOR MOVING SAID MOVABLE MEANS, A FIRST SHAFT FIXED TO SAID CAM FOR ROTATING SAID CAM, SECOND AND THIRD SHAFTS COAXIAL WITH SAID FIRST SHAFT, AND EXTENDING RESPECTIVELY FROM OPPOSITE ENDS THEREOF; A FIRST HELICAL SPRING MEANS SURROUNDING AT LEAST A PORTION OF EACH OF SAID FIRST AND SECOND SHAFTS AND A SECOND HELICAL SPRING MEANS SURROUNDING AT LEAST A PORTION OF EACH OF SAID FIRST AND THIRD SHAFTS, SAID FIRST SPRING MEANS BEING OPERATIVE TO PERMIT ROTATION OF SAID SECOND SHAFT WITH RESPECT TO SAID FIRST SHAFT IN ONE DIRECTION AND TO PREVENT RELATIVE ROTATION 